Light activated curtain pullers, automatic blind controllers and architectural opening covers having automatic positioning capability are known. For example, a U.S patent of Bernot, U.S. Pat. No. 4,864,201 discloses an automatic electromechanical device for opening and closing a curtain in response to light striking a photoelectric cell. The device includes a miniature high torque reversible electric motor and control package to close the drapes at sundown and open the drapes at sunup. The device comprises a dual timer circuit with individual ramping circuits. One timer circuit monitors the sustained presence or absence of light. The other timer regulates the motor drive run time. A flip flop circuit signals the current state of the curtains by providing memory of the last directional movement of the motor.
A more recent approach to automatic blind controllers is disclosed in the U.S. patent of Element et al., U.S. Pat. No. 5,532,560. As shown therein, device a controller includes a reversible motor, a drive circuit, a photosensitive sensor, a user input, a central signal processor, a command circuit and a feed back sensor. The reversible motor is operably connected to the opening and closing device. The drive circuit is connected to the motor for generating a drive signal. The photosensitive sensor generates a sensor signal and the input sensor generates an input signal. The control signal processor is operatively connected to the photosensitive sensor and the user input for combining the signals to produce a control signal.
A further approach to an automatic positioning system for covering an architectural opening is disclosed in an U.S. Patent Application Publication, No. 2003/0098133 of Palmer. The Palmer reference discloses a system that is configured to automatically adjust the position of the covering between a closed position, an open position and one or more intermediate positions in accordance with a geographic location associated with an architectural opening and the time of day.
Notwithstanding the above, it is presently believed that there may be a significant demand for a photosensitive device for warning an individual that the interior light level on one side of a window is greater than the exterior light level on the outside of the window. There should be a demand for devices in accordance with the present invention because such devices provide a warning when it is time to close the curtains based on an actual lighting condition as opposed to an artificially selected time of day. Further, the devices in accordance with the present invention automatically compensate for changes in weather related conditions as for example heavy cloud cover verses bright sun. In addition, the devices in accordance with the present invention also compensate for the amount of artificial lighting in a room and allow an individual to continue to enjoy a view of the exterior by adjusting or turning off the interior lights while maintaining their privacy.
In addition to the above, the devices in accordance with the present invention can be manufactured and sold at a competitive price, are durable and are relatively easy to install. Further, one embodiment of the invention provides an alarm of limited duration and a continued visual indicator until such time the curtains are closed.